Various methods have been used to coat substrates with various titanium compounds. In U.S. Pat. Nos. 3,874,900 and 4,239,536 processes are disclosed for providing a wear resistant surface of titanium carbide and titanium nitride by a chemical vapor deposition process. In the chemical vapor deposition process, titanium tetrachloride is reacted with either ammonia or nitrogen to form titanium nitride. By use of the same chemical vapor deposition process, titanium tetrachloride is reacted with a volatile hydrocarbon such as methane to form a coating of titanium carbide. In the aforementioned patent these are combined to give a composite of titanium carbide and titanium nitride coating.
U.S. Pat. No. 3,868,235 also discloses a process for providing a hard surface. In that process, a metal matrix having a melting point around 2000.degree. F. such as a nickel-chrome-ferrous alloy is applied to a substrate in molten form thereafter a volatile non-metallic organic adhesive is applied to the matrix. Hard metallic carbide such as titanium carbide is deposited on the adhesive layer and the substrate is baked in a furnace below the melting point of the substrate and above the melting point of the matirx alloy whereby the adhesive is volatized, the matrix alloy melts and is bound to the carbide particles and the substrate.
Other processes which can be used to deposit hard compounds of titanium on substrates include sputtering and flame or plasma spraying techniques. Illustrative of these processes are those disclosed in U.S. Pat. Nos. 3,779,720, and 3,895,156.
Chemical vapor deposition processes require use of titanium tetrachloride, a difficult to handle chemical. The process as disclosed in U.S. Pat. No. 3,868,235 requires the use of an organic adhesive which is evolved during processing thus adding a coat to the coated article. Sputtering, plasma, or flame spraying all require special equipment. In addition, plasma or flame spray coating require grinding to get an even coating.